A series of experiments are proposed to determine the mechanism and consequence of elevated glutamate concentration detected at central excitatory synapses. At the source of this question is the whether more than one vesicle can be released at a morphologically defined synaptic junction per invading action potential (multivesicular release; MVR). While MVR has been suggested to occur on cultured hippocampal neurons, an alternative mechanism has recently been proposed. MVR challenges a tenet of neuroscience that states that only one vesicle at each site is released following a stimulus (one-site, one vesicle hypothesis). A model of receptor kinetics will be constructed based on a series of membrane patch experiments from Purkinje neurons of the cerebellum. This model will be combined with manipulations to distinguish the mechanisms that may be responsible for elevated glutamate concentrations. Understanding the source of elevated neurotransmitter concentration and possible consequences will provide valuable insight to central synaptic transmission.